Central distribution of neuronal cell bodies innervating the levator veli palatini muscle and its myosin heavy chain isoform expression pattern - for development of a new palate repair procedure -

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The levator veli palatini (LVP) muscle has a very important role in the complex functions regulating velopharyngeal mechanisms. Previous studies indicate that the LVP muscle is innervated by the glossopharyngeal nerve which is contained efferent and afferent component, and LVP motoneurons are localized in the ambiguous nucleus, and afferen neurons are projected to nucleus solitary tract. In this study, we shall present ; First, in more tooled on the central distribution of the LVP motoneurons and afferent terminals, and investigated location of LVP afferent neuronal cell bodies by using electrophysiological and horseradish peroxidase (HRP)- tracing techniques ; Second, serial muscle cross-sections using monoclonal antibodies specific for myosin heavy chain to characterize the muscle fibers of the LVP muscle HRP-labeled motoneurons in the ambiguous nucleus were separated two rostrocaudally components which were distinguish between rostral division and caudal division, in the rostral division correspond the Botzinger Complex and caudal division correspond rostral ventral respiration group. HRP-labeled afferent neuronal cell bodies were observed in the glossopharyngo-vagal complex ganglion, and HRP-labeled afferent terminals were observed in the bilateral lateral region of nucleus solitary tract. THe LVP muscle was shown to be composed of two muscle compartments by myosin heavy chain isoform expression pattern ; one showed no staining for slow myosin heavy chain isoform but reacted positively for the fast myosin heavy chain isoform, while the other was stained positively for both fast and slow myosin heavy chain isoform. These results suggest it was minutely invested relationship between the myosin heavy chain isoform expression pattern and central distribution of LVP motoneurons or central projections of afferent neurons with regard to active both inspiration and expiration of the LVP muscle.